A. Field of Invention
This invention pertains to a system and method of providing diagnosis for cardiac problems of a patient based on a statistical data base, said problems being generally related to the operation of an implantable cardiac device (ICD) for said patient. The term ICD, or pacemaker is used interchangeably herein to designate pacemakers as well as implantable defibrillators and similar devices used for brady-or tachycardiac therapy and/or defibrillation.
B. Description of the Prior Art
Cardiac pacemakers have become complex over the recent years, with more and more features, such as modes of operations, lead choices, adaptive rate pacing, and mode switching for atrial tachycardias. As a result, typical dual chamber, dual sensor pacemakers presently in use are very complex, requiring more than 40 programmable parameters to be set (either automatically or by a physician) prior to operation. If a pacemaker is not programmed optimally for a patient's condition, and/or the patient's condition changes over time, a fairly natural occurrence, it is often difficult to diagnose the resulting symptoms as either pathological, or due to inappropriate pacemaker operation. Additionally, component failure, while extremely rare, may also result in patient symptoms which are difficult to diagnose. Thus the task of diagnosing problems of patients with pacemakers, whether pacemaker related or pathological, is difficult, requiring extensive specialized training and adds to the cost of providing pacemakers and health care to the patient.
Several solutions have been attempted in the past, in which an expert system was utilized to diagnose cardiac problems. The most common approach n these systems was to automatically interpret electrocardiograms. See Olson, W. H., McConnell, M. V., Sah R. L. Expert System and Diagram for Troubleshooting Dual Chamber Pacemakers, Computers in Cardiology, IEEE Computer Society Press, 1985:53-58; Mark, R. G., Patil, R., Moody,G. An Expert System to Improve Arrythmia Detector Performance in Noise, Journal of Cardiology, 1988 Supplement, S117; U.S. Pat. No. 4,825,869 to Sasmor. However, this approach does not take into consideration patient symptoms, which, in the inventors opinions, provide important diagnostic clues which may help solve the problem being addressed. For example, the Olson reference uses electrocardiograms with pacemaker generated timing diagrams for indicating atrial and ventricular timing problems. However this system may be used only with a dedicated pacemaker having the capability to generate the aforementioned timing diagrams. Moreover, the system is unable to diagnose common problem such as loss of capture, under-sensing and over-sensing of cardiac activity.
The Sasmor reference provides an overall diagnostic scheme making use of physiological signals such as atrial and ventricular intracardiac electrograms, surface electrocardiograms and timing diagrams, event interpretation. However, this system also fails to take into consideration patient symptoms and rules are heuristic and ad hoc, reflecting a particular clinician's bias.
Therefore, generally, most prior systems incorporate merely electrocardiograms interpretation schemes and not a complete diagnosis and fail to take avail themselves of patient symptoms.